Split lttngstudio library in small parts

Make core library a subproject, and link smaller internal libraries to it.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Adding library related files

They were missing from previous commit.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Add utils subproject

The purpose of the utils subproject is to add standalone executable tools
related to the project.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Reoganise library compilation and installation

* We now build only one library liblttngstudio.so from many subdirectories
* Configurable PREFIX install for tests and library

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Unwind skeleton

Empty functions for remote unwind from traces
Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Fix C++ compiler build

Isolate C code with extern C.

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>
Move unwind wrapper code to liblttngstudio

Signed-off-by: Francis Giraldeau <francis.giraldeau@gmail.com>